Baird Atomic Model 135 Scaler (ca. 1961-1965)

The Model 135 scaler was manufactured by Baird-Atomic, Inc., of Cambridge Massachusetts. It was described in January 1962 as “a new all-electronic” scaler “which combines a 5 decade, 5 micro-second scaler and an electronic timer on one chassis... is excellent for both general lab counting work and for use with the most sophisticated automatic sample changing systems.” The phrase “all-electronic scaler” referred to the fact unlike typical binary and decade scalers, the Model 135 did not require a mechanical register. The complete count was indicated by five glow transfer counter tubes. In 1952, the Atomic Instrument Company was the first to incorporate glow transfer tubes into nuclear scalers. They merged with Baird Associates in 1956 and the company was renamed Baird Atomic.

Baird Atomic Model 135 Scaler

The Baird Atomic Model 135 could either count for a preset time or measure the time required to obtain a preset count.

When a glow transfer tube is viewed from the end, a dot of light can be seen moving in a circular path. The dot actually moves through ten discrete positions when making a complete circuit. Each position is numbered (0 to 9) on the outer edge of the tube, much like the hours on a clock.  As such, the count is indicated by the position of the dot of light.

Size: 18" x 19.25" x 9.75"

Range: 0-100,000 counts

Time: 0-10,000 seconds

High Voltage: 0-2,500 volts


  • Nucleonics January 1962, p. 79.
  • Nucleonics May 1952, p. 85.